Air jet commutator



Sept 16, 1958 A. v. BLOCK ErAL AIR JET coMMUTAToR Filed Aug. 12, 1955INVENTOR. @ZW M56/ 7' 4,4/ W

llii.

United.

AIR JET COMMUTATOR Application August 12, 1955, Serial No. 528,139

Claims. (Cl. 20G-81.9)

This invention relates to mechanical commutation devices and the like.

In the ield of mechanical commutation, the desirable characteristics ofan ideal commutator are long life, reliability of operation, high scanspeeds with direct current operation, and large segment selection. Nocommutator exists, however, which is ideal with respect to each of thesefeatures. For example, if the speed of commutation is high, the life ofthe equipment is correspondingly low. Ordinarily the life of acommutator has been limited by contact and rotor wear to only a fewmillion operations.

The subject of this invention provides a lluid jet cornmutator whichsolves the above problems by having no rubbing contact between the rotorand contact arm and by having only impact contact between the contactarms.

The object of this invention, therefore, is to provide a commutator of asimple design but which will give long life, reliability of operation,and can be used at high scan speeds.

A further object of this invention is the elimination of rubbing contactin commutator devices and substituting therefor only impact contact.

The accompanying drawings disclose illustratory concrete embodimentscapable of carrying out the underlying principles of my invention.

Figure 1 shows the uid jet commutator in its application environment;

Figure 2 shows the fluid jet and ribbon type commutator in a blown-upview;

Figure 3 shows a detail view similar to Figure 2 but depicting acantilever type commutator.

Figure 4 is a view along section lines 2-2 in Figure l.

In prior art devices of commutators, the maximum scan rate wasapproximately 30 c. p. s. These commutators are rotating wafer switches,motor type commutators with either rotating brushes or rotatingsegments, or distributor type commutators operating on the camprinciple. The above commutators are limited by a short life at highspeeds due to excessive wear of either the rotor elements or the contactarms. Their designs also inherently introduce poor frequency response.

With the air jet commutator, it is expected that the life of suchcommutator should be in excess of 1,000 hours with scan rates of 200 c.p. s. and switching rates in excess of 50,000 operations/ second. Inaddition, the air jet commutator has a hat frequency spectrum fromdirect current into the megacycle/second region.

Referringto Figures 1 and 2, circular end plates 1 are mounted on eachside of a tubular sleeve 2. Plates 1 are fixed or mounted to anyconvenient support. Mounted in tube 2 is a flywheel 3 which is securedto the central shaft 4. The shaft is rotatably supported in the endplates by means of ball bearings 5. Any convenient means may be used todrive shaft 4 at the desired rate of speed to obtain the proper scanspeed of the air jet.

rates Patent l after closure.

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Bore 7 is drilled longitudinally of the shaft to slightly past itsmid-point position. Bore 8 is drilled radially of the ywheel and centralshaft to intersect the longitudinal bore 7. Screwed into flywheel 3 isthe nipple 10 having a central bore 9 therethrough. The nipple ismounted within the ywheel 3 so that the two bores 8 and 9 are inalignment.

Ribbon 1S is mounted opposite the outlet 16 in nipple 10 between xedrings 11. The ring or posts 11 are secured to the tube 2 by means offasteners 12.

While Figure 1 shows only several of the ribbon like elements forsimplicitys sake, actually a plurality of such ribbon elements arearranged in an annular array as shown in Figure 4.

A dampening device 13 is placed adjacent the ribbon to prevent theribbon from bouncing and giving false operation. The dampener 13 maytake on several forms. For example, in Figure l, the dampener consistsof curved heavy spring element with leather, felt or some otherabsorbent material adhered to the side facing the contact ribbon. Theadjustment of the dampener may be made by screw means 14. In this typeof dampener, the absorbent pad dampens the contact arm as it swings backThe heavy Spring does not deflect appreciably but only serves to bearagainst the adjustment screw.

A second type of dampener which may be used is shown in Figures 2 and 3.The construction is similar to that of Figure l but the spring materialand spacing of the absorbent material from the ribbon is such as toobtain an action wherein the fundamental oscillation of the contactribbon is only broken and the ribbon is allowed to operate only atharmonics which are small and of such a nature as to prohibit contactrecurrence.

Either type dampener, of course, may be used with either type of ribbon(Fig. 1 or Fig. 3).

Figure 3 shows a modification of the air jet commutator; instead of theribbon type contact mechanism, a cantilever system is substitutedtherefor. Thus, a cantilever element 15 is mounted from a post 11 havingcontacts 17,- 18 at one end of the cantilever. The air jet nipple 10 isplaced adjacent a portion of the cantilever as in the modication ofFigures 1 and 2. Dampening mechanism 13 is also used as in the priorstructure of Figures 1 and 2.

Obviously, each of the fixed contacts (17 and 17') has a means by whichelectrical contact may be made with it, such as separate lead 20 whichmay be separately brought through the tubular sleeve 2, as shown inFigure 4. The lead 20 is, of course, insulated from sleeve 2, as shownat 21, when necessary. Likewise, each of the movable contacts (18 and18') are similarly accommodated, as with leads 22.

The operation of the two modifications is identical. Referring toFigures 1 and 2, compressed air is pumped through bore 7 from anyconvenient source. The air passes through bores 7, 8, 9, out exhaust jet16 and impinges against the ribbon 15 or cantilever 15 (Figure 3). Theforce of impingement causes a momentary closure of contacts 17, 18 (or17', 18 in Figure 3).

Shaft 4, meanwhile, is being rotated at the desired rate of speed.Nipple 10 is likewise rotated at the same rate of speed, causingsuccessive impingement of the air jet on the successive ribbons orcantilevers mounted in tube 2. A port 6 is provided in one of the endplates 1 to prevent a build-up of air pressure within the enclosure.

Damping mechanism 13 is regulated to obtain optimum results with respectto bouncing of the cantilever or ribbon elements. This may have to bereadjusted at different scan speeds.

.In `.the actual `construction of the unit, the end plates weremade ofaluminum, theflywheel of brass, the damper of leather and the tube ofphenolic. It is understood however that numerous substitutions ofmaterials may be made without .dep'artingfrom the scope .of myinvention.

Thelnipple,.inflturn,.had anoutletzport of 0:055 diam- -eter with theoutlet spaced 0.008" :from fthe ribbon 'or Acantilever elements..Numerous lother port sizes .and :spaced outlets may be used by ajudicial selection `of combinations.

It is thus evident that only insignificant wear occurs `with Lmyimproved commutation device, and such Awear Aoccurs only at .the Apointof contact .since I the :air jet has a negligible :effect .on the.ribbon `or cantilever elements. Furthermore, :it .is relatively `simpleto compensate ffor `any wear at .the .point of .contact with `the airI-jet commutation system. With a .conservative design .of .ribbon orcantilever elements, the stress inthe felement'sfmay `be :held .atsuch alow valuethat 4many 'hundredrmil-lions of operations .can be obtained.

Obviously many modifications and variations of the present inventionlare possible in the light of the iab'ove teachings. It is therefore ftobe understood that Within .the scope fof Athe appended claims .thevinvention :may 'be practiced otherwise ithan-as specically described.

What is claimedis:

1. In a commutation device, -astatio'na'ryhollow member having aIcylindrical .innerfsurface; .a plurality .of fixed, 'spaced electrical'contacts mounted .annular'ly :on the fcylindrical surface of saidmember; a plurality of movable :annular-ly spaced, electrical .contacts.resilient-ly :mounted 'in vsaid xedmember and disposed .radially*inward and opposite said fixed contacts for yielding engagementtherewith, .a fluid Apressure nozzle having its opening directed at saidmovable contact mounted in said fixed member for rotation in aperipheral plane that includes said contacts to sequentially close amovable contact on a fixed Contact under fluid pressure from said nozzleduring rotation of said nozzle.

2. The device of claim 1 in which said iluid pressure is compressed airand said rhollow stationary member is .provided with an .aperture forexhausting the air Vfrom within it to prevent a pressure Abuild-up inthe device.

3. The device of .claim 2 wherein each said movable contact includes aribbon-like element mounted vbetween two ltXed supports, and the airpressure impinges against said ribbon-like elements.

4. The device ofclaim 2 Yin Whichsaid movable contacts includecantilever elements and the air impinges on the cantilever element toactuate the contacts.

.5. The Adevice of claim 2 .'furtherrincluding damping means mounted insaid stationary member adjacent .the :movable contacts to preventbouncing vof said contacts.

References Cited in `thefiile of this patent UNITED STATES PATENTSI1,322,506 Austin Nov. 25, `19'19 v2,290,725 Bartels et al. July 21,1942 2,298,210 Gulliksen Oct. 6, 41942 2,455,494 Jaynes Dec. 7, -1'9482,609,461 Holcomb et al Sept. 2, :19.52 2,773,665 Berger 'et al. Dec.11, 1956

